Nano-fabrication includes the fabrication of very small structures that have features on the order of 100 nanometers or smaller. One application in which nano-fabrication has had a sizeable impact is in the processing of integrated circuits. The semiconductor processing industry continues to strive for larger production yields while increasing the circuits per unit area formed on a substrate, therefore nano-fabrication becomes increasingly important. Nano-fabrication provides greater process control while allowing continued reduction of the minimum feature dimensions of the structures formed. Other areas of development in which nano-fabrication has been employed include biotechnology, optical technology, mechanical systems, and the like.
An exemplary nano-fabrication technique in use today is commonly referred to as imprint lithography. Exemplary imprint lithography processes are described in detail in numerous publications, such as U.S. Patent Publication No. 2004/0065976, U.S. Patent Publication No. 2004/0065252, and U.S. Pat. No. 6,936,194, all of which are herein incorporated by reference.
An imprint lithography technique disclosed in each of the aforementioned U.S. patent publications and patent includes formation of a relief pattern in a polymeric layer and transferring a pattern corresponding to the relief pattern into an underlying substrate. The substrate may be coupled to a motion stage to obtain a desired positioning to facilitate the patterning process. The patterning process uses a template spaced apart from the substrate and a formable liquid applied between the template and the substrate. The formable liquid is substantially solidified to form a rigid layer that has a pattern conforming to a shape of the surface of the template that contacts the formable liquid. After solidification, the template is separated from the rigid layer such that the template and the substrate are spaced apart. The substrate and the solidified layer are then subjected to additional processes to transfer a relief image into the substrate that corresponds to the pattern in the solidified layer.
During formation of the relief image into the substrate, as drops of the formable liquid spread to fill the template features, the liquid may flow out of the area between the template and the substrate. Some residual material of the imprinting liquid may remain on the template active area. This material may accumulate with each imprint. This accumulation of material on the template may have deleterious effects on subsequent imprints, including but not limited to: change in critical dimension of the printed features, change in height of printed features, change in the surface energy and/or wetting properties of the template surface, increased adhesion between the solidified layer and the contaminated template surface, and increased numbers of patterning defects in the imprint process.
Techniques for cleaning a template surface include removing the template from the imprint lithography system, cleaning the template, re-installing the template, and inspecting the re-installed template. Cleaning the template may include immersing the template in a liquid cleaning solution or cleaning the template in a reactive plasma chamber. These cleaning processes are slow, resulting in costly down time. Liquid cleaning processes may require elevated temperatures and specialized laboratory equipment. Similarly, plasma cleaning may require a vacuum chamber and high temperatures, and may damage the template surface.